I was taught two spaces after a period, so that's what I do. And when I'm finished with a book, it takes a couple of minutes, tops, to find and replace all the double spaces with a single space. The manuscript shrinks a page or two. Big fat hairy deal. It would take more time than it's worth for me to unlearn what I was taught in Miss Herring's class in 10th Grade. (And by the way, Miss Herring was pretty darned good-looking.)